if it is pure alcohol then, it should be 100 percent?

Question

A druggist mixed 100 cc (cubic centimeters) of a 15 % alcohol solution with 50 cc of pure alcohol. Find the percent concentration of the resulting mixture. Round to the nearest tenth of a percent.

 

May someone show me procedure, please?

Answer 1

The original volume contains 15 cc of alcohol in a 100 cc volume because 15% of 100 is 15.  If you add 50 cc of pure alcohol to the original, you would have 15 + 50 = 65 cc of alcohol in a new volume of 100 + 50 = 150 cc.

 

The new percentage of alcohol is 65/150*100% = 43.3 %